From: Peter Zijlstra <peterz@infradead.org>
To: Nadav Amit <namit@vmware.com>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Nadav Amit <nadav.amit@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
linux_dti@icloud.com, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH v7 14/14] module: Prevent module removal racing with text_poke()
Date: Thu, 6 Dec 2018 11:01:12 +0100 [thread overview]
Message-ID: <20181206100112.GE13538@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181205013408.47725-15-namit@vmware.com>
On Tue, Dec 04, 2018 at 05:34:08PM -0800, Nadav Amit wrote:
> It seems dangerous to allow code modifications to take place
> concurrently with module unloading. So take the text_mutex while the
> memory of the module is freed.
Fun detail, only x86 seems to actually take text_mutex while poking
text.
> Signed-off-by: Nadav Amit <namit@vmware.com>
> ---
> kernel/module.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 57c5b23746e7..b45754961143 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -64,6 +64,7 @@
> #include <linux/bsearch.h>
> #include <linux/dynamic_debug.h>
> #include <linux/audit.h>
> +#include <linux/memory.h>
> #include <uapi/linux/module.h>
> #include "module-internal.h"
>
> @@ -2181,6 +2182,9 @@ static void free_module(struct module *mod)
> synchronize_sched();
> mutex_unlock(&module_mutex);
>
> + /* Protect against patching of the module while it is being removed */
> + mutex_lock(&text_mutex);
> +
> /* This may be empty, but that's OK */
> module_restore_mappings(&mod->init_layout);
> module_arch_freeing_init(mod);
> @@ -2194,6 +2198,7 @@ static void free_module(struct module *mod)
> /* Finally, free the core (containing the module structure) */
> module_restore_mappings(&mod->core_layout);
> module_memfree(mod->core_layout.base);
> + mutex_unlock(&text_mutex);
> }
>
> void *__symbol_get(const char *symbol)
> --
> 2.17.1
>
next prev parent reply other threads:[~2018-12-06 10:01 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 1:33 [PATCH v7 00/14] x86/alternative: text_poke() enhancements Nadav Amit
2018-12-05 1:33 ` [PATCH v7 01/14] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Nadav Amit
2018-12-05 1:33 ` [PATCH v7 02/14] x86/jump_label: Use text_poke_early() during early init Nadav Amit
2018-12-05 1:33 ` [PATCH v7 03/14] x86/mm: temporary mm struct Nadav Amit
2018-12-05 1:33 ` [PATCH v7 04/14] fork: provide a function for copying init_mm Nadav Amit
2018-12-05 1:33 ` [PATCH v7 05/14] x86/alternative: initializing temporary mm for patching Nadav Amit
2018-12-05 1:34 ` [PATCH v7 06/14] x86/alternative: use temporary mm for text poking Nadav Amit
2018-12-05 1:34 ` [PATCH v7 07/14] x86/kgdb: avoid redundant comparison of patched code Nadav Amit
2018-12-05 1:34 ` [PATCH v7 08/14] x86/ftrace: Use text_poke_*() infrastructure Nadav Amit
2018-12-06 0:06 ` Nadav Amit
2018-12-06 16:28 ` Ingo Molnar
2018-12-05 1:34 ` [PATCH v7 09/14] x86/kprobes: Instruction pages initialization enhancements Nadav Amit
2018-12-06 13:09 ` Masami Hiramatsu
2018-12-05 1:34 ` [PATCH v7 10/14] x86: avoid W^X being broken during modules loading Nadav Amit
2018-12-05 1:34 ` [PATCH v7 11/14] x86/jump-label: remove support for custom poker Nadav Amit
2018-12-05 1:34 ` [PATCH v7 12/14] x86/alternative: Remove the return value of text_poke_*() Nadav Amit
2018-12-05 1:34 ` [PATCH v7 13/14] module: Do not set nx for module memory before freeing Nadav Amit
2018-12-06 9:57 ` Peter Zijlstra
2018-12-06 17:28 ` Nadav Amit
2018-12-06 11:13 ` Andrea Parri
2018-12-06 18:52 ` Andy Lutomirski
2018-12-06 18:56 ` Nadav Amit
2018-12-06 20:21 ` Edgecombe, Rick P
2018-12-06 20:29 ` Nadav Amit
2018-12-13 14:10 ` Jessica Yu
2018-12-13 17:25 ` Nadav Amit
2018-12-05 1:34 ` [PATCH v7 14/14] module: Prevent module removal racing with text_poke() Nadav Amit
2018-12-06 10:01 ` Peter Zijlstra [this message]
2018-12-06 10:03 ` [PATCH v7 00/14] x86/alternative: text_poke() enhancements Peter Zijlstra
2018-12-10 1:06 ` Nadav Amit
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